1. Field of the Invention
The present invention relates to a pneumatic tire using a long afterglow phosphorescent (i.e., xe2x80x9cphosphorescentxe2x80x9d hereinbelow) rubber composition. More specifically, it relates to a pneumatic tire using a phosphorescent rubber composition in at least a portion of the tire for the purpose of providing the visibility thereof at night or at a dark place and also providing the ornamental design effect to the tire.
2. Description of the Related Art
Many Patent and Utility Model Applications relating to tires using a phosphorescent substance at the side portion thereof, especially the white side ribbon and side letter portions, are published and known in the art (e.g., Japanese Utility Model Publication Nos. 50-156561, 52-85203, 61-73405, 61-93303, and 7-37713 and Japanese Patent Publication Nos. 59-20703 and 4-202339), for the purposes of improving the visibility of tires at night and producing fashionability of tires.
However, when the phosphorescent substance (e.g., a long afterglow phosphorescent pigment) is intended to apply to, for example, the tire side portions by adhering a seal or wappen thereto, they are not able to follow the deformation due to the rolling of the tire, and therefore, the seal or wappen is peeled off or the cracks occur in the coating. Furthermore, although a method for blending the phosphorescent agent into the tire member rubber is disclosed, the tire member rubber contains many ingredients such as carbon black and therefore, the phosphorescent agent cannot be seen at all. In addition, even in the case of white-colored compounding, the phosphorescent agent is masked or hidden by a large amount of titanium dioxide compounded therein and its luminance is much weakened by heavy metals contained in the sulfur.
Furthermore, conventional tires with white side ribbons and side letter generally have black non-contaminating layers located at the uppermost surfaces thereof, followed buffing the non-contaminating layers after vulcanization to expose the white rubber. In this case, since the portion of the light accumulating rubber layer should be shaved to some extent, the phosphorescent layer should be in such a thickness that the substrate layer does not exposed after shaving so that there are problems in the increase of the amount of the rather expensive phosphorescent substances to be used. cl SUMMARY OF INVENTION
Accordingly, the objects of the present invention are to obviate the above-mentioned problems in the prior art and to provide a pneumatic tire having the improved visibility and the improved ornamental design effects during running at night, without impairing the luminance due to the coloring after the vulcanization and the influence of heavy metals in the sulfur, by using the specified phosphorescent substance and by the non-sulfur vulcanization without compounding carbon black.
Other objects of the present invention are to improve the luminance by providing a reflecting layer under the phosphorescent rubber layer, to decrease the amount of the phosphorescent substance to be used by providing a transparent or translucent cover layer above the phosphorescent rubber layer to be able to design the thickness of the phosphorescent rubber layer thin, and to protect the phosphorescent substance which are not strong against moisture by a cover layer.
In accordance with the present invention, there is provided a pneumatic tire having a non-black rubber portion such as side ribbon, side letter, applique provided at the at least one portion thereof, at least a portion of said non-black rubber composition comprising 100 part by weight of at least one synthetic rubber and 5 to 100 parts by weight of strontium aluminate or calcium aluminate a long afterglow phosphorescent (i.e., xe2x80x9cphosphorescentxe2x80x9d hereinbelow) substance having an average particle size of 1 to 100 xcexcm and having no substantial amounts of carbon black and staining antioxidant, and crosslinked with a crosslinking agent other than sulfur.
In accordance with the present invention, there is also provided a pneumatic tire having at least two layer structures of (i) a surface layer composed of a phosphorescent rubber composition layer and (ii) a lower layer of a bright-colored reflecting rubber layer.
In accordance with the present invention, there is further provided a pneumatic tire comprising phosphorescent rubber composition layer a transparent or translucent cover layer located as the upper layer of the phosphorescent rubber composition layer on at least portion of the non-black rubber.
In accordance with the present invention, there is further provided a pneumatic tire comprising the non-black rubber composed of the three layer structure of, in the order from the outer surface of the tire, a transparent or translucent cover layer, a phosphorescent rubber composition layer and a bright-colored reflecting rubber layer.
In accordance with the present invention, there are further provided a pneumatic tire wherein at least the phosphorescent rubber composition of the non-black rubber contains an isobutylene rubber, a pneumatic tire wherein the transparent or translucent cover layer is composed of such a rubber composition, thermoplastic resin or thermoplastic elastomer that the light transmittance of 1 mm thick film is 50% or more, and a pneumatic tire wherein a part of the transparent or translucent cover layer is removed after the vulcanization of the tire.